亚灌木（拉丁语：suffrutex）是一个园艺学名词，不是正式的植物分类学术语。

多指比灌木矮，枝条匍匐的木本多年生植物，其越冬的木本生长一般不超过10-20厘米；以及仅有半木质化和寿命较短（几年）的植物。熏衣草、百里香和杜鹃花科的很多植物如小红莓属于亚灌木植物。

A subshrub (Latin suffrutex) or dwarf shrub is a short woody plant. Prostrate shrub is a related term. "Subshrub" is often used interchangeably with "bush".

Because the criteria are matters of degree rather than of kind, the definition of a subshrub is not sharply distinguishable from that of a shrub; examples of reasons for describing plants as subshrubs include ground-hugging stems or low growth habit. Subshrubs may be largely herbaceous, with overwintering perennial woody growth much lower-growing than deciduous summer growth. Some plants described as subshrubs are only weakly woody and some persist for only for a few years; others however, such as Oldenburgia paradoxa live indefinitely, rooted in rocky cracks.